1. Field of the Invention
The present invention relates to a suspension insulator structured so as to prevent the separation of the cap and pin of the insulator even when shot by a rifle, for example, thus preventing a serious accident such as a line drop of power transmission lines and the like.
2. Related Art Statement
A suspension insulator for supporting a power transmission line and the like is sometimes attacked as a shooting target by a rifle and the like. There has been such a case that when a bullet hits a shed portion of an insulator, a crack extends to a ceramic head porton, and an insulator string is disconnected by lightning and the like thereafter, or sometimes broken down to pieces, and thereby resulting in insufficient functioning of the suspension insulator. As a result, the broken conductor and/or electric failure of a power transmission line occurs to cause an unexpected disastrous accident. Such accidents have occurred frequently in North America, South America, Australia and other places where high-speed bullets are used for hunting. Therefore, the crack-resistant strength of the insulator shell was improved by changing the material from feldspathic ceramics to alumina-containing ceramics, but when an insulator is shot by a rifle, it is impossible to completely prevent a crack from extending to the head portion of the insulator.